1. Field of the Invention
This invention relates to a recording/reproducing control apparatus and more particularly, is applicable to a data recorder as an external memory unit for computers.
2. Description of the Related Art
Conventionally, in this type of the magnetic recording/reproducing apparatus, there is proposed a data recorder composed of the ID-1 format by which desired data can be reproduced in a high density by sequentially and helically forming recording tracks onto a magnetic tape (ANSI x3.175-1990 19[mm] Type ID-1 Recorded Instrumentation).
More specifically, as shown in FIG. 1, this type of the data recorder is arranged such that a magnetic tape 1 is wound around a rotary drum rotating at a predetermined speed and caused to travel at a predetermined speed so that recording tracks TR (TR1, TR2, TR3, TR4, TR1, TR2, . . . ) are sequentially and helically formed by a magnetic head mounted on the rotary drum to thereby record desired data to the recording track TR1.
Further, at this time, the data recorder has recording tracks TA, CTL, TC formed at the upper and lower ends of the magnetic tape 1 and extending in the lengthwise direction thereof so that the track set identification data (ID) of the recording tracks TR is recorded to the recording track CTL.
Here, the track set ID is an absolute positional information starting from the leading head of the magnetic tape 1, is held between predetermined synchronizing signals and is recorded to the recording track TR at a 4-track cycle. Further, the recording tracks TA and TC can record user's management data and the like to thereby reproduce the recording tracks TA, CTL, TC so that data recorded to the recording track TR in a high density can be easily searched.
Further, when data is recorded to the recording tracks TR, the data recorder records the data together with an error detection/correction parity code composed of a product code to thereby securely record and reproduce desired data. More specifically, as shown in FIG. 2, the data recorder fetches data DATA in a predetermined unit (=36,108[BYTE]) and then divides the data DATA into 306 blocks and adds a Reed-Solomon error detection/correction code (i.e., composed of a C2 code) to each block.
Further, after the block has been divided into first and second fields FIELD 0 and FIELD 1, the data recorder adds a Reed-Solomon error detection/correction code (i.e., composed of a C1 code) to each of the fields FIELD 0 and FIELD 1 so that the code C1 is perpendicular to the code C2. With this arrangement, the data recorder can improve a bit error rate by correcting the error of reproduced data by using the C1 and C2 codes when data is reproduced.
Further, when the data DATA added with the codes C1 and C2 as described above is recorded to the magnetic tape 1, the data recorder carries out an interleave processing to each recording track TR so that even if a drop out and the like are caused, the data DATA can be securely reproduced. More specifically, the data recorder records the data DATA input in the sequence of arrows a1, a2, . . . , an-1, an, an+1, an+2, . . . , ax-1, ax by changing the input sequence thereof as shown by arrows b1, b2, . . . , bn-1, bn so that the data DATA is interleaved.
Further, at this time, the data recorder records the data DATA which is added a synchronization signal SYNC and sync block data ID to each predetermined unit (hereinafter, referred to as a sync block), as well as preamble and postamble data as a whole. With this arrangement, when the data is reproduced, a magnetic recording/reproducing apparatus can reproduce the synchronization signal SYNC, the sync block data ID and the data DATA by using the track sync data contained in the preamble as a reference and carry out the data interleave processing by using the synchronization signal SYNC and sync block data ID as a reference.
Further, the execution of the data interleave processing can effectively prevent errors exceeding the error correction capability of the codes C1 and C2 from concentrating to one point even if the drop out and the like are caused.
Incidentally, the ID-1 format data recorder for recording/reproducing desired data as described above is arranged to ensure a bit error ratio of about b 10.sup.-10 which is sufficient in practical use mainly as a data recording/reproducing apparatus for measuring data. It is contemplated that if the bit error rate can be improved to about 10.sup.-15, this apparatus can be applied to the magnetic tape unit of computer systems used in, for example, banks and the like for the storage of very important data. Therefore, the merit obtained by using this type of the data recorder is improved and thus it can be applied to wider fields.